Automatic transmission



y 5, 1953 J. c. TAYVLOR 2,637,217

AUTOMATIC TRANSMISSION Filed Aug. 8, 1947 2 SHEETSSI-IEET l May 5, 1953 J. c. TAYLOR 2,637,217

AUTOMATIC TRANSMISSION Filed Aug. 8, 1947 Patented May 5, 1953 UNITED STATES PATENT OFFICE AUTOMATIC TRANSMISSION Michigan Application August 8, 1947, Serial No. 767,505

This invention relates to automatic gear changing mechanisms and particularly to mechanisms of this general class which are primarily designed and intended for use in connection with automotive vehicles.

Automatic gear changing mechanisms in which gear ratios are changed from time to time by the automatic operation of devices which are brought devices being under the control of the governor.

The present invention contemplates the utilization of a gear changing mechanism in which the actual gear changing operations are effected by power supplied by fluid under pressure, the flow .of fluid under pressure being controlled not only by the speed responsive device or governor but likewise by manually operable instrumentalities in the nature of valves, including a valve associated with a throttle operating mechanism and a :valve associated with a manually operable gear shift rod, the arrangement being such that the mechanism must of necessity remain inopera- .tive until the operator of the vehicle performs two preliminary operations, 1. e. until theoperator actuates a gear shift lever which is normally in neutral position but which must be moved from that position in one direction if the vehicle is to be driven forwardly by its power plant or :moved in the reverse direction if the vehicle is to move rearwardly, and also operates a throttle control mechanism to eifect increase of fuel supply to the engine. The mechanism as an entirety being thus inoperative until and unless the operator makes two deliberate preliminary moves, adequate safeguards against accidental actuation are provided. After the engine has low gear and the shifting to intermediate and higher gear ratios will be automatically effected as the speed of the car increases, likewise the shiftingfrom a higher to a lower gear being automatically effected as the speed of the car decreases. I The mechanism also includes a switch in the electrical connection between the battery and :the starter-switch of the-car, this added switch 3 Claims. (Cl. 74-472) been started, and after the gear shift lever has been actuated and the-throttle control mech- .anism also actuated, the vehicle will start in brought .out;

being positioned adjacent a member which is operated by the gear shift lever and being so operatively associated therewith that the switch remains open, and the starting mechanism inoperative, unless and until the gear shift rod is in neutral position. Thus it is impossible for an operator to inadvertently or accidentally start the engine while the vehicle is in gear, as sometimes occurs with gear changing mechanisms of other types. While the gear changing operations are automatically effected while the vehicle is under way, the mechanism is to a certain extent still under control of the operator of the vehicle in that, whenever great power is needed suddenly while the vehicle is in progress the controlling action of the governor may be overcome by the operator who will simply operate the throttle control mechanism to effect the widest possible opening of the throttle, the throttle control mechanism being so connected to the governor as to modify its action temporarily and. cause the gear changing mechanism to automatically reduce the gear ratio while the emergency exists.

The mechanism includes a number of novel features of construction, to be hereinafter described at length and which are shown on the accompanying drawings in which:

Figure 1 is a diagrammatic showing of the mechanism as an entirety, no attempt having been made to show the several operating parts in the relationship which they bear to each other when assembled .in a vehicle, and certain of the parts being shown out of proportion to others in order that the operative relationship of each part to the other, parts may most clearly be Figures 2 and 3 are diagrams showing certain of the fluid pressure controlling valves inpositions which are different from those which they are shown to occupy in Figure 1, corresponding to different gear ratios;

Figure 4 is a section on line i4 of Figure 1;

Figure 5 is a diagram of the starter circuit showing the switch which normally opens the circuit unless and until the gearshift rod is moved to neutral position;

Figure 6 is a diagram showing connections between the fuel control lever and other elements of the mechanism, including the speed responsive device or governor; and

Figure 7 illustrates a detail in side elevation. The gearing shown in Figure 1 will be recognized as being largely conventional, the transmission shaft being indicated at It, propeller shaft at ll, these shafts being in alignment and adapted to be operatively connected and disconnected by means of a clutch generally indicated at M, the clutch M being of the fluid pressure responsive type and being operative when fluid pressure is maintained in the chamber M against the face of piston M and being inoperative when the pressure of the fluid is relieved. Gear A on transmission shaft to is in constant mesh with gear B on a parallel shaft 52. Aligned with shaft [2 is a short shaft i3 and means is provided for directly connecting shafts i2 and 13, so that they rotate at the same speed, or for connecting them through a planetary system so that shaft l3 will rotate at less speed than shaft [2.

This means includes the clutch N with its piston N adapted to be moved on its clutch engaging stroke when fluid under pressure is introduced into the chamber N and to be disengaged when this fluid pressure is relieved, together with the planetary system including the drum rotatably mounted on shaft I2 and the cylindrical interior surface of which is toothed so that it comprises an internal gear, and the three planetary gears 0 the teeth of which mesh with the internal teeth of the drum 0 and the external teeth formed upon the hub portion 52 of shaft I2. Other details of the planetary gearing are conventional and need not be described. Drum O is partially encircled by a brake band l5, most clearly seen in Figure 4, one end of which is anchored to a stationary part It and the other end of which is connected by means of a rod I! to a piston l8 movable in cylinder I9. A spring 29 located within the cylinder normally maintains the piston l 8 in some such position as it is shown in Figure 4 and the band [5 out of gripping engagement with the surface of the drum 0. Introduction of fluid under pressure into the pressure chamber 2| of the cylinder will, however, effect engagement of band I 5 with the cylindrical surface of the drum 0 and will prevent the drum from rotating.

Mounted for free rotation on shaft !3 are gears D and F respectively, the teeth of gear D being in constant mesh with the teeth of ear E of shaft II and the teeth of gear F being in constant mesh with the teeth of a reverse idler gear G which in turn mesh with those of a gear 1-! fixed on shaft II. For clutching either gear D or gear F to shaft l3 a shiftable synchronizer 2% of generally conventional character is employed, this synchronizer being splined on shaft !3 and movable longitudinally thereon and provided with two series of internal teeth (not ill strated) one such series being adapted to be brought into meshing engagement with gear F rigidly mounted upon a sleeve integral with gear F, the synchronizer being shown in this position in dotted lines in Figure 1, and the second internal gear of the synchronizer 23 being adapted to be brought into meshing engagement with a similar gear rigid with gear D. the synchronizer being shown in full lines in Figure 1 to be operatively connecting gear D to shaft 23 and gear F being free to rotate on shaft l3. By the application of fluid under pressure to the chambers M N and 2| of the several fluid pressure responsive instrumentalities described gear ratio chan e is effected. The mechanism for supplying such fluid under pressure to one or the other of these instrumentalities. and simultaneously venting the other two, will now be described.

A constant source of fluid under pressure is needed and this may conveniently be a gear pump, such a pump being diagrammatically indicated at U in Figure 1, one rotor of the pump being mounted upon the shaft 24 and the teeth of gear C, which is also fixed on shaft 24, meshing with those of gear B previously described so that the pump is in operation whenever the transmission shaft H) is revolving. The output of the pump is directed into a distributing main 25 which has four branches and a terminal end, indicated by the numerals 25, 26a, 23b, 21 and 28, respectively. The outflow of oil through each of the branches 2G and 27 is controlled by a manually operable valve hereinafter to be described, and the fluid discharged from the terminal end 28 of the main 25 is likewise valve controlled but may not be interrupted, the purpose of the valve being to distribute the outflowin oil rather than to interrupt the flow.

This distributing valve is indicated at V in Figure l and is in the nature of a valve of generally cylindrical nature having circumferential ribs V and V the cylindrical outer surfaces of which make close sliding engagement with the cylindrical inner surface of the valve casing K, the valve body V as an entirety being freely slidable axially of its casing. Valve V is under control of a governor or speed responsive device which is generally indicated at L and may be of any suitable type but preferably is of the centrifugal type including weight members 33 mounted on the ends of arms 3| of bell crank levers pivoted at 32, each such lever having a second arm 33 engaging the outer race 3 of a ball or roll hear-- ing the inner race 35 of which is mounted upon the end of the valve body V. By means of the pivots the several weighted levers are connected to, and move bodily with, a hub 36 supported upon the end of a shaft 31. Rigidly mounted upon shaft 31 is a spiral gear 38 and the teeth of gear 38 mesh with those of gear I which is fixed upon the propeller shaft H. The upper end of the casing K of the valve is enlarged to comprise a suitable housing for the speed responsive mechanism thus described,

A helical spring 48 opposes the action of the speed responsive device, one end of this spring bearing against the end of the valve V which is remote from the speed responsive device, and the other end being supported by a shiftable abutment member ll. Abutment member 4| is toothed on one side to provide a rack 47. and meshing with the teeth of this rack are those of a pinion 63 rotatably mounted in a recessformed in the wall .of the casing By rotating pinion 43 the position of the shiftable abutment 4! may be altered and the tension in the spring 4!) modified, hence the degree of opposition of the spring to the movements of the valve V under the action. of the speed responsive device changed from time to time as may be desired. The shaft upon which pinion 43 is mounted extends outwardly through the wall of easing K and upon its outer end is fixed a second pinion 1 (Figure 7) the teeth of which mesh with those of a rack 45 the movements of which may be controlled in any suitable manner from the operators position, for instance by means of a link 46 having an operat ing handle 41 within convenient reach of the operator and a series of teeth 48, the link 46 being longitudinally shifted to bring any selected interdental space into registry with. the edge of a stationary member 49 so that, when member 49 is positioned intermediate two teeth, the link is held against longitudinal movement and hence the shiftable abutment 4| held against movement longitudinally within the casing K.

Valve V has formed therein an axial bore within which is housed a helical spring and a rod 5I the inner end of which bears against one end of spring 50. Rod 5I also passes through an aligned bore in the shiftable abutment 4| and has fixed upon its outer end a disc 52 adapted to be acted upon by the shorter arm 53 of a bell crank lever pivotally supported at 54 to the wall of casing K. The longer arm 55 of the bell crank lever projects beyond the end of the casing and is connected by means of a link 55 to one end of a lever 58 fulcrumed at 59, the opposite end of lever 58 being connected by a link 60 to the pedal 51 which is normally urged into the position in which it is shown in Figure 6 by a spring 6|. The upper end of lever 58 is also connected to the carburetor of the vehicle by means of a link 64. Depression of pedal 5'! thus increases the supply of fuel to the engine of the vehicle and likewise rocks the bell crank lever 55 which in turn longitudinally advances rod 5! against the action of spring 50. Also connected to link 50, intermediate its ends, is one end of a lever 66 which extends laterally of and is rigidly connected to a rotatable valve 61 provided with a port 98 which may be brought into register with the terminal end of the branched duct 21 of the fluid supply main 25. Depression of pedal 5! will therefore also effect movement of valve 51 and the arrangement is such that the valve closes the port at the end of the branch duct 21 when pedal S'I-is actuated, thus preventing escape of liquid from main 25 through this duct.

Branch duct 26 previously referred to leads to a cylindrical casing I0 having aligned ports II and I2 in its wall. Slidably fitting within the cylindrical casing I0 is a rod I3 which may be designated a gear shift rod inasmuch as it is operatively connected to a gear shift lever (not illustrated) which lever is adapted to be manually manipulated by the operator of the vehicle. Rod I3 is cut away at I l to provide an annular recess or chamber which may be brought into register with ports 'II and i2, thus permitting fluid to flow from main 25 through the outer escape or by-pass aperture I2, or the rod may be moved longitudinally by means of the gear shift lever into position (a shown in Figure l) to interrupt this flow. It is thus clear that the fluid under pressure which is delivered by the pump into the main 25 may escape through by-pass port I2 which is controlled by a valve which may be actuated by the gear shift lever, or may escape through the port 63 in valve 61, or may pass from the terminal end 28 of main 25 into the casing K through port I5 in casing K. It is only when port I2 and 68 are both closed by their associated valves that the fluid supplied will be under sufficient pressure to cause automatic operation of the gear ratio changing mechanism. Such fluid under pressure, for the purpose of operating the gear changing mechanism, will flow through branch ducts 26a and 2612, the flow being controlled by valve mechanism to be hereinafter more fully described.

It will be observed from Figure 1 that, in addition to port 15, casing K is provided with six additional ports indicated, respectively, at "I6, 11, I8, I9, and BI, ports It and I1 being fluid dis charge ports through which fluid may escape from the interior of easing K into a suitable receptacle, it being understood that this fluid, which is preferably oil, is collected for re-use to gether with the fluid which may escape through tons l? and P and of valves S and S port 68 of valve 61, the fluid which may escape through port 12 of valve casing I0, and the fluid escaping through other ports hereinafter to be described, all such fluid being preferably collected in a sump into whichextends the intake pipe of the gear pump U.

= Ports I8 and I9 communicate through conduits 84 and 85 with the opposite ends of a cylinder which is generally indicated at 86 and ports 80 and 8| communicate through ducts or conduits 81 and 88 with the opposite ends of a cylinder generally indicated at B9.

A piston P slidable within cylinder 89 may be caused to reciprocate by applying pressure upon one face and permitting the fluid in the opposite end of the cylinder to escape, and likewise piston P may thu be moved from end to end of the cylinder 86. Piston P is connected by means of a piston rod 90 to a cylindrical slide valve S closely fitting within a cylindrical chamber formed within the valve casing 9| and piston P is connected by piston rod 92 with a cylindrical slide valve S reciprocable within a cylindrical chamber which is preferably formed in the same valve casing 9 I. Slide valve S is cut away at 93 and 94 to provide annular passageways for fluid around the valve and slide valve S is cut away at 95, 96 and 91, to provide three passages by means of which fluid may pass around that valve. Formed in the walls of the cylindrical chambers which receive the slide valves S and S are a series of ports indicated respectively at I 00, IOI, I02, I03, I04, I05, I06, I07 and I08. Of these ports, those indicated at I00 and IOI are in continuouscommunication with the fluid pressure main 25 through branch ducts 26a and 26b and constitute fluid supply ports, and ports I02, I03, I05 and I06 respectively comprise ports which may be designated fluid escape ports; fluid passing outwardly through these ports being collected in the sump previously mentioned for the collection of such fluid. Fluid outlet port I04 is in constant communication with chamber M of clutch M, the connecting duct being indicated at IIO. Fluid outlet port I0! is in constant communication with chamber N of clutch N the connecting duct being indicated at III, and fluid outlet port I08 is in constant communication with space 2I of cylinder I9 previously described, the connecting duct being indicated at I I2.

, In the automatic operation of the mechanism the governor control valve V, when the vehicle is underway, will be longitudinally moved under the influence of the governor and, against the action of spring 40, as previously stated. The position of valve V determines the direction of ,-flow of fluid to and from cylinders 86 and'-89, thus effecting reciprocatory movements of pis- Valves S and S directly control the passage of fluid under pump pressure to the several fluid pressure responsive devices described, i. e. the clutches M and N and the cylinder I9. When the valves V, S and S are in the positions in which they are illustrated in Figure l and the rod 13 and valve 6? are positioned as shown in that figure, the output of the pump passes through port IOI, port I9I port I03, duet H2, and into cylinder IS, the band I5 will grip the drum 0 to halt the rotation thereof and the drive will be from the transmission shaft I0 through gears A and B. shaft i2, the planetary assembly, shaft I3, synchronizer 23, and gears D and E to the propeller shaft I I, the drive being thus at low gear.

In Figure. 2a of 'the drawings are illustrated arranged for intermediate speed ratio drive.

valve V,- pistons P and P and slide valves S and E in the positions which these parts occupy wher;

I will be observed that, by reason of the .action of the governor the valve V has been moved so that the port 8t has been brought into communication with the discharge port it, thus permitting fluid to escape from the right hand and of cylinder 85. Ports l3 and '49 are blocked and port 15 is in communication with port 8| so that piston P has been moved to the right hand end of cylinder 89, pulling after it the slide valve S. Port Iii-8 has thus been brought into communication with the lay-pass port #35 the pressure in cylinder i9 is relieved, causing band i to release drum 0. At the same time communication has been established between port lfli and the fluid chamber N of clutch N so that that clutch is engaged, planetary movement ceases, and the drive is from the transmission shaft it through gears A and B, shafts l2 and I3, gears D and E to the propeller shaft 1 1. Further movement of the valve V in the same direction brings about the condition indicated by the diagram of Figure 3 in which the piston P has also been moved to the right, bringing with it slide valve 8, the port I00 being thus brought into communictaion with the chamber M of clutch M and the drive being thus direct from transmission shaft lb through clutch M to the propeller shaft H. When the valve S is moved to the position shown in Figure 3, the chambe N of clutch N is brought into communication with the by-pass port I 62 and the pressure in that chamber relieved, thus disconnecting shafts l2 and i3. Reversal of movement of slide valve V, as the speed of the vehicle decreases, will cause the gear ratio to be changed in reverse sequence. Automatic change in gear ratio will thus be of" fected from. time to time as the vehicle proceeds, so long as some pressure is applied to the throttle operating pedal and the discharge port in the end of branch duct 27 is closed and the gear shift rod 23 closes port 12.

If, during forward movement of the vehicle, it is desired to develop the greatest possible amount of power, as when there is an emergency, the operator will depress the accelerator pedal to the maximum extent. As a result the bell crank lever 55 is rocked, spring 50 will be compressed,

and valve V will be moved under the influence of the spring, causing change in the distribution of fluid under pressure and a shift to a lower gear ratio. When the speed of the vehicle in creases sufiiciently, the action of the governor will automatically restore the drive'to high gear.

Greatest economy in the use of fuel maybe obtained if the normal tension in spring 40 be kept as low as possible. If this be done the governor will be able to force slide valve V rather easily to the high speed position of Figure 3 and thus facilitate shifting to high gear at low vehicle speeds. By adjusting the abutment 4| to increase the normal tension in the spring the shifting to hi h gear may be caused to occur at higher vehicle speeds. By manipulating the hanfile t! therefore the operator may vary substantially the vehicle speeds at which gear shifts occur.

If gear shift rod 13 is moved to the rear (to the right in Figure 1) from its neutral position, port 12 will of course be blocked as before and, upon depression of the throttle lever, valve 61 will close the outlet of duct 21, thus causing fluid pressure to build up in main 25. Rearward shifting of rod 13 likewise causes the synchronizer 23 to-separate from gear D and operatively engage gear F which is rigid with gear F, so that the drive will be through the gear train F, G, H. Movement of the synchronizer is effected by movement of the shifter fork 23a, this fork having an aperture through which the reduced portion 73a of rod '3 freely passes. Shoulders 13b and of rod 13 alternately contact with the shifter fork 23a and effect movements of this fork as the rod is moved.

It is not desirable to have automatic adjustment to high gear when the vehicle is in reverse and for that reason means is provided to prevent movement of slide valve S when gear shift rod 13 is shifted rearwardly. To thus lock valve S against movement a locking rod H5 is provided. One end of this red is received within an annular groove 73c formed in rod. 13, one end of this groove, indicated at 13) bein inclined, preferably conical, and comprising a, cam adapted to act upon the end of locking rod H5, when rod 13 reaches the end of its rearward movement, and to thrust this rod I I5 toward valve S which will then be in low gear drive position, and cause its end to enter the annular groove S formed in that valve. So long as the rod 73 is maintained in its rearward position of adjustment valve S will be held against movement and hence it will not be possible for the vehicle to be driven at high speed in a rearward direction. When the rod '13 is moved to neutral or forward position rod H5 will unlock valve S which may then be reciprocated by fluid under pressure in the manner heretofore explained.

Gear shift rod 13 is also employed to operate a switch in the starter circuit of the vehicle, the arrangement being such that this switch is closed, and it is thus possible to start the engine, only when the gear shift rod is in neutral position. Such a switch in the starter circuit is diagrammatically illustrated in Figures 1 and 5, being indicated at I20. The movable blade or contact member of the switch is associated with a member [2| which is supported for movement along a fixed path and one end of which bears against rod 13, such contact being maintained at all times by a spring I22 which acts upon it. When rod 13 is in neutral position the enlarged portion 13h thereof, which in effect comprises a cam having inclined portions at its ends, directly engages member IN and the switch is closed. The engine of the vehicle may then be started as the circuit through the starter solenoid may be closed in the usual manner. If the rod 13 has previously been moved either to its forward or its rear position, however, the switch I20 will be open and the engine may not be started. The advantages of this arrangement will be apparent.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. An automatic gear changing transmission for automotive Vehicles including in combination, a source of fluid under pressure, a conduit into which fluid under pressure is discharged, said conduit having three spaced fluid discharge ports for the simultaneous discharge of three streams .of fluid in parallel, a valve associated with each discharge port for controlling escape of fluid therefrom, a gear shift rod associated with one of said valves, the valve being disposed to close the associated port when the rod is moved from neutral position, a throttle control operativ'ely connected to a second valve, a governor operatively connected to the third valve, and a propeller shaft to which said governor is operatively connected and by which it may be driven, the arrrangement being such that insufficient fluid under pressure is delivered through said conduit to the port controlled by said third valve unless said two first mentioned valves are closed.

2. An automatic change gear transmission for automotive vehicles comprising in combination, a governor operatively connected to a propeller shaft and directly responsive to changes in speed of that shaft, a throttle operating means, a source of fluid under pressure, a plurality of fluid pressure responsive devices adapted to be actuated by fluid delivered from said source, a clutch associated with each such device, a conduit system for receiving fluid from said source and transmitting it to said devices through three parallel conduits and means for controlling the flow of fluid through said conduit system to said devices, said means including a flrst valve arranged to be operated by said governor, a second valve operatively associated with said throttle operating means, a third valve, each of said valves being associated with one, and only one, of said conduits, and a gear shift rod, said third valve being operatively associated with said gear shift rod, and being in port closing position only when said gear shift rod has been moved from its neutral position.

3. In an automatic change gear transmission, in combination, a source of fluid under pressure, a plurality of fluid pressure responsive clutches, conduits leading from said source to said clutches respectively, a plurality of independently operable valves for controlling fluid flow through said conduits respectively, a piston for actuating each of such valves, cylinders in which said pistons move, conduits for connecting the ends of said cylinders, respectively, to the source of fluid under pressure, a valve device controlling the flow 0f fluid to said cylinders, and a governor operatively connected to said valve device.

JOSEPH C. TAYLOR.

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